header fix

docs.it4i/dgx2/job_execution.md

@@ -83,7 +83,7 @@ kru0052@cn202:~$ exit
 !!! tip
     Submit the interactive job using the `salloc` command.
 
-### Job Execution
+## Job Execution
 
 The DGX-2 machine runs only a bare-bone, minimal operating system. Users are expected to run
 **[Apptainer/Singularity][1]** containers in order to enrich the environment according to the needs.
@@ -93,7 +93,7 @@ Containers (Docker images) optimized for DGX-2 may be downloaded from
 copy the docker nvcr.io link from the Pull Command section. This link may be directly used
 to download the container via Apptainer/Singularity, see the example below:
 
-#### Example - Apptainer/Singularity Run Tensorflow
+### Example - Apptainer/Singularity Run Tensorflow
 
 ```console
 [kru0052@login2.barbora ~] $ salloc -A PROJECT-ID -p qdgx --time=02:00:00